I have a Desktop which runs on Windows XP and a laptop which runs in Ubuntu 12.04.

Recently I have set up a wireless router in order to be able to access internet on my laptop through wifi. The laptop connects to the wifi at ease, but is unable to transfer any data. Only when I switch on my laptop for the first time, it is able to transfer some data for just few minutes, after which it even fails to ping the router.

Ping to router shows: "ping: sendmsg: No buffer space available", but the wifi still shows to be connected.

@Anuj - the way this site works is by constantly refining your question with relevant information and replies. Please can you edit your question and add the relevant comments above and delete your comments. Thanks.
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fossfreedom♦Sep 27 '12 at 16:43

@kamil - similar comment above - post an answer and edit your answer as you "converse" with the OP. Thanks.
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fossfreedom♦Sep 27 '12 at 16:44

Myself and many others (according to my Google searches) are having this same problem with Ubuntu 11.10, whereas for me also I never had any trouble with network drivers in 10.x or even 11.04.

EDIT: Cause of problem NOT resolved, after all :'(. The following might still be involved in some way, so I'll leave it here for others to reference. But it turned out NOT to solve the problem. Neither did reverting to a 2.6.x kernel.

My system is using the r8169 driver for my Realtek 8168 chip Ethernet port (on the motherboard in my case. Note: 8168 -- not 8169!)

I finally got onto this issue when I found this post. I quickly confirmed that my 8168 card was using the r8169 driver by running ...

sudo lshw -class network

..., which takes a while -- just be patient. :-)

You can see the driver being used in the configuration: line ... Example: ...

Then I mostly followed the instructions in this post to install and activate the correct driver, changing specific paths as required to match my system. Note that the driver download site does not mention the v3.x.x kernel (only 2.4.x and 2.6.x) But it works just fine anyway.

If you have only one network interface, then you should be all set by this stage.

Unfortunately, it wasn't quite that simple for me, because I also had a second card installed, which did have an actual 8169 chip on it! :-/ So, I couldn't just leave the r8169 driver disabled.

To fix this, I renamed the /lib/module/your-kernel-version/drivers/net/r8169.bak file (the autorun.sh driver installer script renamed it) back to r8169.ko and edited /etc/modules as follows ...

# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
loop
lp
r8168
r8169

... [last two lines added] hoping that this would force the modules to be loaded in that same order, thus avoiding modprobe picking up the r8169 driver for the wrong card. It worked!

To the OP ... I'm updating this for the benefit of other people searching for a solution, because it comes up pretty high in Google results. Hope you don't mind.

Uhmm, thank you for the advice. Actually I use wimax interface on which I experience the problems. The driver which is used is i2400m with the firmware=i6050-fw-usb-1.5.sbcf.
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OleksaOct 31 '11 at 8:43

Yeah ... and I've just discovered that the problem has NOT actually gone away. At this point, I can only believe that there's a kernel fault, above the layer of network driver modules. I read in some other random post that someone else had come to the same conclusion. Their fix was to roll back to 2.6.x kernel. Easier said than done.
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gruvinOct 31 '11 at 22:02

Ehmm, you know when I restart NM the issue goes on. Perhaps to try to re-compile NM? I tried but failed due to inconsistent dependencies.
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OleksaNov 2 '11 at 23:45

Well it's very annoying issue. What to do? It appears when I use wimax connection session.
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OleksaNov 11 '11 at 0:06